Articulospora - Phylogeny vs morphology

Area of Science:

• Mycology
• Fungal Taxonomy
• Molecular Systematics

Background:

• The taxonomy of aquatic hyphomycetes, including the genus Articulospora, traditionally relies on the morphology of their asexual reproductive structures (conidia).
• Articulospora tetracladia, a globally distributed species, exhibits dimorphic conidia in natural populations, varying in branching levels, which complicates classification.
• Previous classifications have been challenged by molecular data, necessitating a re-evaluation of species boundaries within Articulospora.

Purpose of the Study:

• To investigate the phylogenetic relationships within the genus Articulospora using molecular data.
• To assess the utility of different gene regions as DNA barcodes for differentiating Articulospora and related genera.
• To clarify the taxonomic status of Articulospora tetracladia and the significance of conidial dimorphism.

Main Methods:

• DNA extraction and amplification from 20 isolates of Articulospora and Fontanospora.
• Sequencing of three gene regions: internal transcribed spacer (ITS), D1/D2 large subunit ribosomal DNA, and cytochrome c oxidase subunit I (COX1).
• Phylogenetic analysis and comparison of sequence data to morphological observations.

Main Results:

• Molecular analyses did not fully support species separation based solely on conidial branching patterns.
• The internal transcribed spacer (ITS) region proved to be the most effective barcode, providing adequate resolution to distinguish between tested Articulospora and Fontanospora species.
• D1/D2 primers showed amplification but limited resolution, while COX1 gene sequencing was inconsistent.

Conclusions:

• A broad taxonomic concept for Articulospora tetracladia, encompassing strains with dimorphic conidia, is proposed.
• The ITS gene region is recommended as a reliable molecular marker for the taxonomy of Articulospora and related aquatic hyphomycetes.
• Molecular data integration is crucial for refining fungal taxonomy, especially for species with variable morphological characteristics.